1. Field of the Invention
The present invention relates to an engine sound synthesizer and an engine sound synthesizing method for synthesizing an engine sound that sounds much closer to an actual engine sound on the basis of the actual engine sound. The present invention further relates to a game machine and a motor vehicle each incorporating the engine sound synthesizer. The present invention still further relates to a computer program for engine sound synthesis, a game program incorporating the computer program, and a recording medium containing the computer program.
2. Description of Related Art
A prior-art engine sound synthesizer is disclosed in Japanese Unexamined Patent Publication No. 2000-010576. In the prior-art engine sound synthesizer disclosed in this patent publication, an engine driving state is divided into a plurality of driving state ranges on the basis of an accelerator opening degree and an engine rotation speed which are used as parameters. An engine sound is preliminarily recorded in a driving state at around a median of each of the driving state ranges. A digital data entity of an engine sound segment in a time frame during which a crank shaft is rotated in one combustion cycle is extracted from the recorded engine sound. The engine sound data entities thus extracted for the respective driving state ranges are preliminarily stored in a storage section. In the engine sound synthesizer, an engine sound data entity for a driving state range specified by inputs of the accelerator opening degree and the engine rotation speed is read out of the storage section and repeatedly reproduced for generation of a synthetic engine sound. For realization of the unique indefiniteness of the actual engine sound, at least one of the loudness, frequency and tone of the synthetic engine sound to be generated is changed every time the engine sound data entity is reproduced.
However, the prior-art engine sound synthesizer stores only one engine sound data entity for each of the driving state ranges provided by dividing the engine driving state on the basis of the accelerator opening degree and the engine rotation speed which are used as the parameters. Therefore, it is impossible to generate a synthetic engine sound that is equivalent to the actual engine sound simply by modifying the single engine sound data entity in various ways.